Hydraulic actuator



Sept, 16, 1969 H. K. HETZ ET AL HYDRAULIC ACTUATOR 4 Sheets-Sheet 1 Filed Feb. 19, 1968 INVENTORS.

WARREN H. BRAND GEORGE B.

DABINETT ATT Y S,

Sept. 16, 1969 H. K. HETZ ETAL HYDRAULIC ACTUATOR 4 Sheets-Sheet 2 INVENTORS. HEINZ K. HETZ WARREN H.BRAND BY GEORGE B. DABINETT ATT'YS.

4 Sheets-Sheet 5 Filed Feb. 19, 1968 fir/1174.

ATTYS.

Sept. 16, 1969 H. K. HETZ ETAL 3,467,017

HYDRAULIC ACTUATOR Filed Feb. 19, 1968 4 Sheets-Sheet 4 INVENTORSZ HEINZ K.HET'Z WARREN H. BRAND GEORGE B. DABINETT' ATTYS.

United States Patent 3,467,017 HYDRAULIC ACTUATOR Heinz K. Hetz, Doylestown, and Warren H. Brand, Blue Bell, Pa., and George B. Dabinett, Willingboro, N.J., assignors to Yarway Corporation, Blue Bell, Pa., a corporation of Pennsylvania Filed Feb. 19, 1968, Ser. No. 706,516 Int. Cl. F041) 49/08, 9/10; F04c 15/04 US. Cl. 103-38 13 Claims ABSTRACT OF THE DISCLOSURE A pump assembly, in which a pumping diaphragm is mounted within a cavity and is flexed by a pulsating fluid produced by an orbiting-piston, is provided with a hydraulically adjustable guide which engages the piston to regulate the fluid pulses and the pumping cavity displacement. Hydraulic cylinders receive pistons mounted diametrically on the guide, and a valve is provided to control the fluid pressure therein in response to a control signal, the hydraulic energy being produced by reaction forces between the orbiting-piston and the guide.

This invention relates to pumps, and more particularly, it relates to mechanisms for hydraulically adjusting the displacement of pumps.

In fluid process applications utilizing proportioning pumps, it is desirable to provide the proportioning pumps with automatic adjusting means capable of reacting quickly and accurately to control signals so that the process flow conditions are controlled within a desired range. At present, the accurate adjustment of pumps of this type requires an operator, and, in some cases, adjustment may be made manually only after the pump has been shut-down. Also, proportioning pumps are frequently installed in remote locations thereby making their manual adjustment more diflicult.

Heretofore, the automatic adjustment of proportioning pumps has required the application of relatively large forces through complex linkages in order to eflect the desired adjustment; and a supply of high pressure air or hydraulic fluid from an external source is often required to provide adequate force. Therefore, the installation of this type of pump is limited to locations in which these utilities are available, notwithstanding the expense of installing and maintaining these utilities for pumps which are installed in remote locations.

In addition to the inefficiencies inherent with these adjustment arrangements, there exist spatial considerations which arise in conjunction with the installation of pumps in confined locations. The large and complex linkage arrangements associated with previous adjusting mechanisms must therefore be avoided if compact installation is to be achieved.

With the foregoing in mind, it is an object of this invention to provide an improved pump assembly in which the pump displacement is rapidly and accurately adjusted in response to an automatic control signal.

It is another object of this invention to provide a novel pump assembly having eflicient means for hydraulically adjusting pump displacement without the need for an external source of energy to effect the desired adjustment.

As a further object, this invention provides as compact, hydraulic adjusting means for proportioning pumps to facilitate their installation in remote or confined spaces.

In addition to these objects, this invention provides means for hydraulically adjusting the displacement of a pump in which a pumping diaphragm is flexed in response to pulsating fluid produced by an orbiting-piston.

3,467,017 Patented Sept. 16, 1969 The piston is mounted and reciprocated within a rotor by adjustable guide means mounted eccentric to the rotor axis and in engagement with the piston. The adjustment of the guide means is provided by piston-like protrusion means secured thereto and positioned for sliding within fluid pressure chambers. In response to the rotation of the rotor, reaction forces between the piston and the guide means pressurize fluid contained within the fluid pressure chambers and valve means, interconnected between the chambers by conduit means, regulates the fluid pressure therewithin in response to a control signal to thereby adjust the position of the guide means and regulate the pump displacement.

In addition to the foregoing, other objects, features and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a top plan view of a pump assembly embodying the present invention;

FIG. 2 is a view in end elevation of the pump assembly of FIG. 1 having portions broken away to illustrate the interior thereof, the guide means being adjusted to the zero position;

FIGS. 3 and 4 are enlarged sectional views of the pump assembly of FIG. 1 taken along lines 33 and 4-4 respectively, but with the guide means adjusted to the maximum position;

FIG. 5 is an enlarged fragmentary view of the pump assembly of FIG. 4 taken along line 55;

FIG. 6 is an enlarged fragmentary view, partially broken away and sectioned, and illustrating the valve means of the linkage assembly of FIG. 4;

FIG. 7 is an enlarged fragmentary view of the adjustable check valve shown in FIG. 4;

FIG. 8 is a schematic diagram of alternate means for actuating the valve means;

FIG. 9 is a fragmentary elevational view partially broken away and sectioned, and illustrating a modification of the valve operating means of FIG. 4; and

FIG. 10 is a view in end elevation of the modification illustrated in FIG. 9.

Referring now to the drawings, FIG. 1 illustrates a pump assembly or device comprising a casing 10 having at one end a work fluid inlet 11 and work fluid outlet 12 (FIG. 2). At the other end, a gear unit 14 provides means for transmitting power from a drive motor 15 to a drive shaft 16 (FIG. 3).

Within the interior of the casing 10, a wall member 18 divides the casing into a rotor housing portion or sump 19 and a diaphragm housing portion 20. A flexible diaphragm 21 is positioned between two apertured diaphragm plates 22 and 23 and is mounted within the diaphragm housing 20 to form a pumping cavity 24 and a Work cavity 25. Contained within the inlet 11 and the outlet 12 are conventional non-return or check valves which cooperate upon flexure of the diaphragm 21 to elfect the flow of work fluid upwardly through the work cavity 25.

In the illustrated pump, flexure of the diaphragm 21 occurs in response to a pulsating fluid which is provided wihin the pumping cavity 24 by means of a pumping arrangement shown generally at 26 (FIG. 3). In this arrangement, a rotor 27 is mounted in the rotor housing or sump 19 by means of roller bearings 28 and 29. The rotor 27 has a radial recess 30 in which a driven member or orbiting-piston 31 is mounted for reciprocating movement, the piston 31 being biased radially outwardly thereof by means of a spring 32. Fluid communication is provided between the recess 30 and the pumping cavity 24 by means of a fluid passageway 33 which terminates in a port 34 adjacent to the pumping cavity 24. The rotor 27 is integral with the shaft 16 which imparts rotary motion thereto when the drive motor 15 is energized.

In order to pulsate the pumping fluid within the pumping cavity 24, guide means 35 is provided for reciprocating the piston 31 as the rotor 27 is rotated. Referring now to FIG. 4, the guide means 35 has a substantially cylindrical inner peripheral surface 36 which engages the outwardly protruding portion of the piston 31, reciprocation of the piston or driven member 31 occurring when the guide means 35 is positioned eccentric to the rotor axis of rotation and the piston 31 is thereby periodically cammed inwardly against the spring 32. When the sump 19 is filled with a pumping fluid, for example to the level indicated at A, reciprocation of the piston 31 will pulsate a pumping fluid within the rotor passageway 33 and the pumping cavity 24 to flex the diaphragm 21 and effect a pumping action in the work cavity 25, the magnitude of the fluid pulses determining the displacement of the work cavity 25. The magnitude of the fluid pulses is controlled by adjusting the eccentricity of the guide means 35. For a more complete description of the operation and construction details of this type of pump assembly, reference is made to US. Patent No. 3,374,750 (US. patent application, Ser. No. 568,528) which discloses a pump similar to the one described here and having manually operable means for adjusting the eccentricity of the guide means relative to the rotor.

In accordance with the primary objects of the present invention, compact and eflicient hydraulic actuator means is provided for rapidly and accurately adjusting the work cavity displacement in response to a control signal. The displacement is adjusted by regulating the pulsation in the. work cavity, the pulsation being regulated by adjusting the eccentricity of the guide means with respect to the rotor axis. To this end, the guide means 35 is mounted within the rotor housing 19 for sliding movement transversely to the rotor axis of rotation. In the present instance, the guide means 35 is provided with means forming diametrically opposed piston-like protrusions 37 and 38 which extend outwardly from the guide means and slidably support the same for movement along an axis of adjustment which, in the present instance is perpendicular to the rotor axis. The protrusions 37 and 38 terminate at each end thereof in pressure surfaces 39 and 40 respectively. The guide means is thereby mounted for movement along the adjustment axis to vary its eccentricity.

The hydraulic energy required to effect the desired adjustment of the guide means is provided by alternating reaction forces produced as the piston sweeps around the inner surface of the guide means. A reaction force component directed along the adjustment axis is normally counteracted by hydraulic fluid pressure within a chamber in a hydraulic actuator positioned adjacent to the guide means on its axis of adjustment. The fluid pressure is regulated to permit controlled axial displacement of the guide means by the reaction forces. To this end, actuator means forming a fluid pressure chamber 41 has a smooth central bore or cylinder 42 which slidably receives the protrusion 37 to thereby mount the guide means 35 within the sump 19. A fluid pressure chamber 45 is thereby defined and confronts the pressure surface 39. In the preferred embodiment of the present invention, means forming a fluid pressure chamber 47 has a smooth bore 46 which slidably receives the protrusion 38. A fluid pressure chamber 48 is thereby defined and confronts the pressure surface 40. The chamber 45 is sealed from the sump 19 by a sealing ring 44, and the chamber 48 is sealed from the sump 19 in a similar manner by a sealing ring 49. Thus, fluid pressure chambers are provided on opposite sides of the guide means on its axis of adjustment. The guide means is maintained in an eccentric position when fluid is confined within the chambers, and the guide means is adjusted when the pressure in a selected one of the chambers is regulated by bleeding-off a .4 small quantity of fluid, the guide means thereby being axially displaced toward the lower-pressure chamber under the influence of the reaction forces.

In order to regulate the fluid pressure within the chamber 45, and within the chamber 48, valve means providing fluid communication between each of the chambers and the sump is provided. To this end, the valve means includes conduit means having conventional fluid couplings 51 and 52 respectively mounted on the chamber-forming members 41 and 47, and a tubular member 53 is connected to the couplings to provide fluid communication therebetween.

For the purpose of affording fluid flow through the conduit means to thereby bleed-off fluid and regulate the pressure within each of the chambers 45 and 48, the valve means has a valve body 58 formed integral with the chamber member 47 and having internal fluid passageways formed therein to provide selective fluid communication between the sump and each of the chambers 45 and 48. A passageway 54 formed in the valve body 58 opens at one end into the sump and at the other end into a cylindrical recess 55. The recess is connected to the chamber 45 through a passageway 56 and the tube 53, and is connected to the chamber 48 through a passageway 57 formed within the valve body and offset slightly from the passageway 56. A slide valve member 59 within the recess 55 (FIG. 6) has an enlarged body portion 59a and a reduced body portion 59b. An axial port 60 formed therein extends beyond the enlarged portion 59a and terminates in an aperture 61 in the reduced portion 59b to thereby provide fluid communication between the sump and the chamber 48 when the reduced portion 59b registers with the passageway 57. Thus, selective paths of fluid communication are provided between the sump and each of the chambers 45 and 48, the paths being selected by longitudinal displacement of the slide valve member from an intermediate flow-blocking position to first and second regulated-flow positions.

Therefore, when the valve member 59 is in its intermediate position as shown in FIGS. 4 and 6, fluid flow between each of the chambers 45 and 48 and the sump 19 is blocked, and the guide means 34 is maintained in a predetermined eccentric position, the fluid confined within these chambers counteracting the alternating reaction forces caused by rotor rotation. When the valve member 59 is moved rightward into its first position, a path for fluid flow is established from the chamber 45 through the tube 53 and passageway 56, into the cylindrical recess 55, and into the sump 19 through the passageway 54. Movement of the slide valve member 59 leftward or into its second position provides a fiuid flow path from the chamber 48, through the aperture 61 and axial port 60, and through the passageway '54 into the sump.

For the purpose of automatically actuating the valve member 59 and thereby adjusting the eccentricity of the guide means 35, means is provided to operate the valve member in response to a control signal. To this end, the slide valve member 59 has a stem 63 which extends outwardly from the valve body 58, a conventional O-ring sealing member 64 being mounted on the stem 63 to prevent leaking of hydraulic fluid. Threadedly or otherwise fixedly. secured to the pressure surface 40 on the protrution 38 is a rod member 65 which has a portion thereof extending outwardly from the chamber 48, and, similarly to the valve stem 63, O-ring seals 67 and 68 engage the rod 65 to prevent the leakage of fluid outwardly from the chamber 48.

The outwardly extending portions of the valve stem and rod are interconnected at their ends by linkage means,

and, in accordance with a principal object of the invention, the linkage means is formed to provide proportional relative movement between the rod 65 and the valve member 59. In the present instance, movement of the linkage means displaces the slide valve member from its intermediate flow-blocking position to one of its regulated flow positions, and the displacement of the guide means along its axis returns the valve member to its intermediate flow-blocking position to arrest further guide means displacement. To this end, the medial portion of a rigid yoke 69 is pivotally mounted on the end of the rod 65. One end of the yoke 69 is connected to the valve stem 63 by conventional fasteners, and the other end of the yoke 69 is connected on an operating rod 70, which is connected to means movable in response to a control signal, in this instance a conventional diaphragm-type air cylinder shown generally at 71 which may be provided with a vent for regulating the leakage of control air therefrom. The air cylinder 71 is mounted on the valve body 58 by means of a bracket 72 which is fastened to the valve body by means of screw fasteners 73, and the air cylinder and linkage assembly is protected from dirt and damage by means of a cover 74 fastened to the valve body 58 by thumb screws 75. Also, passages 90 and 91 are provided in the valve body 58 to return to the sump hydraulic fluid which has leaked passed the O-ring 67.

If desired, the valve operating means may be electrically actuated, for example by a two-way solenoid connected to the valve stem 63a for displacing the valve stem in alternate directions in response to a control signal. This arrangement, illustrated schematically in FIG. 8, may also include a conventional error signal generator connected to the rod 65a for producing an error signal in response to the position of the guide means. The error signal, when fed into the control signal generator, provides a feedback for the valve operating means so that the guide means is quickly and accurately adjusted to the desired eccentric position.

In view of the range of control air pressures which are available at various installations, it is desirable to provide means for adjusting the proportional relationship between the pump displacement and the control pressure magnitude. To this end, the means for moving the linkage means may be mounted for vertical adjustment relative to the guide means adjustment axis, this arrangement being illustrated in a modified form of the present invention in FIGS. 9 and 10. In this arrangement, a bracket 172 is fastened on a valve body 158 and extends outwardly therefrom to terminate in a downturned flange 17211. A plate 173 having an inturned lip 173a mounts a conventional air cylinder 171. The plate 173 is mounted on the flange 172a by a locking screw 176 which passes through a slot 179 formed in the plate 173. A slot 169a is also formed in the lower end of the yoke 169, the slots 179 and 169a cooperating to permit the plate 173 to move vertically. The plate is adjusted vertically upon rotation of an adjusting screw 178 which is tapped into the lip 173a, the locking screw 176 firmly securing the plate and air cylinder to the bracket to maintain the desired adjustment. Thus, when the air cylinder 171 is adjusted upwardly, a lesser magnitude of control air pressure is required to etfect a predetermined change in the pump displacement, since the yoke 169 and the valve stem 163 are displaced by a smaller displacement of the operating rod 170. Conversely, when the air cylinder 171 is adjusted downwardly, a greater magnitude of control air pressure is required to effect a predetermined change in the displacement of the pump, since the yoke 169 and the valve stem 163 require greater displacement of the operating rod 170 to elfect a change in their positions. Furthermore, in order to provide means for adjusting the pump capacity setting in theevent of 'a failure in the control air pressure, it is desirable to mount an adjusting screw 100 and lockout 101 (FIG. 9) on the air cylinder 171 in alignment with the operating rod 170. The rod 170 may thereby be longitudinally displaced to set the pump at a desired capacity setting by manually turning the adjusting screw 100 and locking it with the locknut 101.

As shown in FIGS. 2 and 5, visual determination of the pumping capacity setting is provided by a elongated arm 76 secured to the operating rod 70. The arm extends outwardly from the cover 74 through a slot 77 to register with a scale 78 on the cover. In addition to indicating the pump capacity setting, the arm 76 may be set manually to adjust the eccentricity of the guide means in the absence of the air cylinder 71. Moreover, in the modification shown in FIGS. 9 and 10, a cover 174 is slotted adjacent to its thumb screws 175 to permit the cover 174 to be rotated to maintain the alignment between a similar slot 177 and elongated arm 170a when the air cylinder 171 is adjusted.

Operating in conjunction with the aforementioned valve means to regulate the pressure within each of the chambers 45 and 48, check means is provided for affording flow of hydraulic fluid in one direction from the sump 19 into the chamber 45, and, in a similar manner into the chamber 48. The check means operates to prevent movement of the guide means in a direction opposite to the adjustment direction when the slide valve member is in one of its regulated-flow positions. For this purpose, a conventional ball check valve 79 having an adjustable spring pressure is positioned within a fluid passageway 80 formed with the chamber 41 and connecting the chamber 45 with the sump. A ball check valve 81 is similarly positioned within a fluid passageway 82 formed within the chamber member 47 to permit fluid to flow from the sump into the chamber 48, and, in the present instance the check valve 81 is adjusted by means of an adjustable seat in the form of a hollow adjusting screw 83 as shown in FIG. 7. Thus, for example, this check means cooperates to permit fluid contained within the sump to enter the chamber 45 when the pressure is lowered therein by rightward movement of the guide means protrusion 37 in response to the periodic rightward component of the reaction forces, to thereby prevent guide means displacement opposite to the desired adjustment direction.

In order to ensure optimum performance of the actuator means when the pump is started and the discharge pressures are relatively low, means is provided for biasing the guide means on the adjustment axis and eccentric to the rotor axis of rotation. To this end, the biasing means includes a conventional compression spring mounted in a selected one of the chambers, in the present instance the right-hand chamber 48, to bias the guide means 35 leftward. In this manner, the spring provides a positive force which assists the alternating reaction forces in shifting the guide means when the alternating forces are lowest in magnitude and frictional forces tending to retard the displacement of the guide means are greatest in magnitude.

In operation, the rotor housing 19 is filled with a hydraulic fluid to the level indicated at A, and the electric motor 15 is energized. Rotation of the rotor 27 urges the pumping piston 31 into camming engagement with the inner surface 36 of the guide means 35, the compression spring 95 biasing the guide means leftward into engagement with the pumping piston 31. As noted heretofore, the stroke of the piston 31 and the pump displacement is regulated by adjusting the degree of eccentricity between the rotor 27 and the guide means 35, so that when the guide means 35 is positioned outwardly, or to the left of the rotor axis as shown in full lines in FIG. 4, the displacement of working cavity 25 is at its maximum. Conversely, when the guide means 35 is moved to the right in the position indicated in the broken lines in FIG. 4, the displacement of the working cavity 25 is at its minimum. As the rotor 27 is rotated, reaction forces, developed between the piston 31 and the inner surface 36 of the guide means, are transmitted in alternation through the two protrusions 37 and 38 to pressurize the fluid contained within the chambers 45 and 48. The fluid pressure counteracts these forces when the slide valve member 59 blocks fluid communication between the rotor housing interior or sump 19 and chambers 45 and 48, so that the guide means 35 is maintained in its fixed eccentric position.

The displacement of the pumping and work cavities is changed by adjusting the eccentricity of the guide means. The guide means is moved to the right as seen in FIG. 4 in response to a decrease in the control air pressure. To this end, the operating rod 70 moves rightward and rotates the yoke 69 on its medial pivotal connection to move the slide valve member 59 to the left and out of its normal flow-blocking position. Pressurized fluid within the right-hand chamber 48 is thereby bled through the passageway 57, into the aperture 61, through the port 60 and the passageway 54, and into the sump 19. The guide means moves toward the right under the influence of the periodic rightward reaction forces produced by the orbiting-piston. As the guide means moves toward the right, the pressure in the left-hand chamber 45 is reduced. Fluid is then free to flow through the check valve 79 and passageway 80 and into the lefthand chamber to counteract the reaction forces tending to displace the guide means leftward in the direction opposite to the desired adjustment direction. Further movement of the guide means 35 to the right causes the rod 65 and the link 69 to return the valve member 59 to its intermediate flow-blocking position to thereby arrest the movement of the guide means.

The guide means is moved to the left in response to an increase in the control air pressure within the air cylinder. This moves the operating rod 70 leftward and rotates the yoke 69 on its medial pivotal connection to move the valve member 59 to the right and out of its normal flow-blocking position. Pressurized fluid within the left-hand chamber 45 is thereby bled through the tube 53 and passage means 56, 55 and 54 respectively into the sump. The guide means then moves toward the left under the influence of the periodic leftward reaction forces. As the guide moves to the left, the pressure in the right-hand chamber is reduced. Fluid is then permitted to flow through the check valve 81 into the righthand chamber 48 to counteract the reaction forces which tend to displace the guide means rightward in the direction opposite to the desired adjustment direction. Further movement of the guide means 35 to the left causes the rod 65 and the link 69 to return the valve member 59 to its flow-blocking position to arrest further movement of the guide means. In this manner, the eccentricity of guide means 35 and the pump displacement is adju'sted in proportion to the control pressure applied within the air cylinder 71, and the pump displacement is adjusted rapidly and accurately to a predetermined value without further control signals and without overshooting the displacement called for by the initial control signal.

Thus, from the foregoing description it can be seen that hydraulic adjusting means has now been provided for pumps, which in addition to being eflicient, is compact and provides rapid and accurate adjustment of the pump displacement in response to a control signal. Although the present invention is particularly suited for use with pumps, nevertheless it should be apparent that it may be used effectively to provide adjustment for devices having a driven member mounted for reciprocating movement.

We claim:

1. In a device having a driven member mounted for reciprocal movement and guide means engaging the member to control the reciprocal movement thereof, the guide means being slidably mounted for adjustment on an axis, the reaction forces of said member tending to displace said guide means on said axis alternately in opposite directions; means for hydraulically adjusting the guide means, said adjusting means including hydraulic actuator means providing a fluid pressure chamber adjacent to the guide means, said guide means cooperating with the chamber so that fluid pressure in the chamber normally counteracts said reaction forces, valve means in fluid communication with the chamber for regulating the fluid pressure therein to permit controlled displacement of the guide means by said reaction forces, and means for operating said valve means, whereby upon reciprocation of said member and operation of the valve means the guide means is displaced on said axis and the reciprocal movement of said member is adjusted.

2. A device in accordance with claim 1 wherein said actuator means includes means forming a piston-like therefrom and terminating in a pressure surface; means protrusion on the guide means extending outwardly slidably mounting the protrusion on the adjustment axis and forming a fluid pressure chamber confronting the pressure surface for containing a pressure fluid therewithin, whereby the fluid pressure within the chamber counteracts said reaction forces tending to axially displace the guide means alternately in opposite directions.

3. A device in accordance with claim 1 wherein the device includes a sump adapted to contain a fluid; and said valve means includes conduit means providing fluid communication between the chamber and said sump, a valve member cooperating with said conduit means selectively operable between opposite positions affording regulated fluid flow through said conduit means in opposite directions between said sump and said chamber, said member having an intermediate position normally blocking flow through said conduit means, the first of said opposite regulated-flow positions affording flow outwardly from the chamber into said sump to reduce the fluid pressure in the chamber and permit controlled displacement of the guide means toward the chamber, the second of said regulated-flow positions affording flow from said sump into the chamber to replenish the fluid in the chamber and permit controlled displacement of the guide means away from the chamber, whereby the eccentricity of the guide means is adjusted in response to the position of said flow-affording means.

4. A device in accordance with claim 3 wherein said valve operating means includes linkage means connected to said valve member; and means for moving said linkage means to displace said valve member from its intermediate flow-blocking position toward one of its regulated-flow positions to initiate displacement of the guide means along its adjustment axis, said linkage means being connected to the guide means to thereby move the valve member in a direction away from the regulated-flow position toward its intermediate flow-blocking position upon a predetermined displacement of the guide means along its axis, whereby the guide means cooperates with the linkage and the valve member to provide controlled displace of the guide means.

5. A device in accordance with claim 1 wherein said actuator means includes means providing piston-like protrusions on the guide means extending outwardly therefrom on its axis of adjustment and terminating in a pressure surface at each end; means slidably mounting the protrusions and forming a fluid pressure chamber confronting each of the pressure surfaces for containing a pressure fluid therewithin, whereby the fluid pressure in the chambers counteracts reaction forces tending to axially displace the guide means alternately in opposite directions.

6. A device in accordance with claim 5 wherein the device includes a sump adapted to contain a fluid; and said valve means includes conduit means providing selec- -tive fluid communication between each chamber and the sump; a valve body having fluid passage means formed therein in fluid communication with said conduit means; a slide valve member in said passage means having an intermediate position normally blocking fluid flow between each chamber and the sump and being longitudinally moveable into a first fluid-flow regulating position to afford regulated fluid flow between the sump and a first one of the chambers and a second fluid-flow regulating position to afford regulated fluid flow between the sump and a second one of the chambers; and check means providing fluid communication in one direction from the sump to each of the chambers, so that movement of the slide valve member to a regulated-flow position affords bleeding of fluid from one of the chambers to lower the pressure therein and permit the guide means to move along said adjustment axis, the guide means thereby drawing fluid through said check means into the other of the chambers to counteract reaction forces tending to displace the guide means opposite to a desired adjustment direction.

7. A device in accordance with claim 6' wherein said valve operating means comprises linkage means and means for moving said linkage means, said linkage means including a yoke having one end connected to said valve member and its other end pivotally connected to said moving means, said yoke being pivotally mounted intermediate its ends on the guide means to permit displacement of the valve member from its intermediate flow-blocking position to a regulated-flow position by said moving means, the guide means thereupon being displaced on its axis by the reaction forces and operating to pivot the yoke about its moving means connection in response to a predetermined displacement of the guide means, whereby said slide valve member is returned from the regulated-flow position to its intermediate flow-blocking position to arrest further displacement of the guide means.

8. A device in accordance with claim 7 wherein said other end of said yoke is slotted to slidably receive therein said pivotally connected moving means, and said moving means is mounted for adjustment relative to said slotted yoke, whereby the proportion between the displacement of said slide valve member and the displacement of said moving means is varied when said moving means is adjusted relative to said yoke.

9. A device in accordance with claim 7 wherein said moving means includes a fluid expansion cylinder mounted on the device and adapted to be connected to a supply of control fluid, a rod pivotally connected to said yoke and cooperating with said cylinder for movement in response to control fuid pressure supplied thereto, whereby movement of said rod pivots said yoke and displaces said valve member selectively between its intermediate flow-blocking and its regulated-flow positions in response to control fluid pressure and displacement of the guide means.

10. In a pump assembly comprising a casing providing therein a work cavity and a sump, a rotary pump in the sump for pumping fluid through the work cavity, the rotary pump including a rotor having a radial pumping recess and mounted for rotation within the sump, a pumping piston mounted in the rotor recess and biased radially outwardly thereof, guide means having a substantiall cylindrical inner peripheral surface engaging the piston to reciprocate the piston upon rotor rotation, the guide means being slidably mounted for adjustment on an axis transverse to the rotor axis of rotation, the guide means tending to be displaced in opposite directions along the adjustment axis by reaction forces produced by the reciprocating piston; the improvement comprising means for hydraulically adjusting the guide means, said hydraulic adjusting means including hydraulic actuators disposed on said adjustment axis on opopsite sides of the guide means, said actuators each having a fluid pressure chamber formed therein for containing a pressure fluid, the guide means cooperating with each chamber so that fluid pressure therein normally counteracts said reaction forces, valve means in fluid communication with each chamber for regulating the fluid pressure therein to permit controlled displacement of the guide means by the reaction forces, and means for operating said valve means, whereby upon reciprocation of the piston and operation of said valve means the guide means is displaced on said axis and the reciprocation of the piston is adjusted.

11. A pump assembly in accordance with claim 10 wherein said hydraulic actuator means includes means providing piston-like protrusions on the guide means extending outwardly therefrom in opposite directions on its axis of adjustment and terminating in a pressure surface at each end; means slidably mounting the protrusions and forming a fluid pressure chamber confronting each of the pressure surfaces for containing pressure therewithin, whereby the fluid pressure in the chambers counteracts reaction forces tending to axially displace the guide means alternately in opposite directions.

12. A pump assembly in accordance with claim 10 wherein said valve means includes conduit means providing selective fluid communication between each chamber and the sump; a valve body having fluid passage means formed therein in fluid communication with said conduit means; a slide valve member in said passage means having an intermediate position normally blocking fluid flow between each chamber and the sump and being longitudinally movable into a first fluid-flow regulating position to afford regulated fluid flow between the sump and a first one of the chambers and a second fluid-flow regulating position to afford regulated fluid flow between the sump and a second one of the chambers; and check means providing fluid communication in one direction from the sump to each of the chambers, so that movement of the slide valve member to a regulated flow position affords bleeding of fluid from one of the chambers to lower the pressure therein and permit the guide means to move along said adjustment axis, the guide means thereby drawing fluid through said check means into the other of the chambers to counteract reaction forces tending to displace the guide means opposite to a desired adjustment direction.

13. A device in accordance with claim 12 wherein said valve operating means includes linkage means connected to said valve member; and means for moving said linkage means to displace said valve member from its intermediate flow-blocking position toward one of its regulated-flow positions to initiate displacement of the guide means along its adjustment axis, said linkage means being connected to the guide means to thereby move the valve member in a direction away from the regulatedflow position twoard its intermediate flow-blocking position upon a predetermined displacement of the guide means along its axis, whereby the guide means cooperates with the linkage and the valve member to provide controlled displacement of the guide means.

References Cited UNITED STATES PATENTS 2,669,935 2/ 1954 Tucker. 2,727,359 12/1955 Staller l0338 X 3,015,212 l/1962 Kraift et al. 3,107,624 10/ 1963 Williams 103-38 X LEONARD H. GERIN, Primary Examiner US. Cl. X.R.

mg? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,467,017 Dated September 16, 1969 Inventor(s) Heinz K. Hetz, Warren H, Brand and George B. Dabim It is certified that error appears in the above-identified patent, and that said Letters Patent are hereby corrected as shown below:

Column 1 line 66, change "as" (second Qccurrence) toa--- Column 6, line 19, before "adjustment" udd---desired--- line 23, change "with" to----with1'.n---

Column 8, delete lines 12 and 13 and substitute therefor--- protrusion on the guide means extending outwardly therefrom and terminating in a pressure surfaee; means--- Column 9, line 44, change "fuid" to---fluid-- line 66, change "oposite" to---opposite--- Column 10, line 52, change "twoard" to---toward-- STGNED AND SEALED (SEAL) .Atteat:

WILLIAM L. SCIHUYLER, JR. Edward Cozmnissione: of Patents Attesting Officer 

